CN1179043A - Variance changeble time slot width in TDM/TDMA system - Google Patents
Variance changeble time slot width in TDM/TDMA system Download PDFInfo
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- CN1179043A CN1179043A CN 97119657 CN97119657A CN1179043A CN 1179043 A CN1179043 A CN 1179043A CN 97119657 CN97119657 CN 97119657 CN 97119657 A CN97119657 A CN 97119657A CN 1179043 A CN1179043 A CN 1179043A
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Abstract
A system protocol for a communication system having a number of time frames (402), each of the number of time frames having a predetermined period of time divided into a number of discrete multiple time slots (452), wherein a total width of all of the number of discrete multiple time slots is equal to the predetermined period of time, a given number of the number of discrete multiple time slots are aggregated (aggregated time slots) (440), and a preamble (450) is provided at a beginning of the aggregated time slots and is not replicated anywhere else in the aggregated time slots.
Description
Present invention generally relates to broadband RF communication protocol, particularly such agreement, it concentrates the pay(useful) load of time slot to allow the conversion of many speed and/or digital coding analog signal in the TDM/TDMA system.
In TDM/TDMA (time division multiplexing, time division multiple access) digital communication system, Nmax the time slot that is organized as normal rate frame structure is multiplexed on each FDD (frequency division multiplex) carrier equipment.Each time slot is being represented a direction of a basic normal speed duplex channel.A duplex channel (or carrier wave) comprises a up channel and a down channel, and interrelates with an agreement that is suitable for the TDM/TDMA system.
According to the agreement of TDM/TDMA system, send in each time slot of the time frame of one group of bit (being called a serial data (burst)) in given frequency (or carrier wave).Time frame reproduces with the fixedly duration of Tf.Each serial data is divided into two parts in traditional TDM/TDMA agreement; An extention and a pay(useful) load part.Bit number in the pay(useful) load part obtains the bit rate Bc of each full speed channel divided by frame rate Tf.
Usually Nmax full speed channel time division multiplexing in traditional TDM/TDMA system to each on the duplexing carrier wave.For requiring bit rate to be higher than the application of Bc, in each time frame, two or more Nmax time slot allocation are given with a user.Under these situations, data are carried out segmentation in a plurality of pay(useful) loads place (each time slot all comprises additional and the pay(useful) load part) for transmitting here, and in the receiving terminal of the link data of rearranging.This process is called to be used or the multi-slot method repeatedly.In any case the time slot in multi-slot operation need not in a time frame continuously because segmentation is all wanted in load.
As carry, in the multi-slot operation or in the time slot of concentrating, each all comprises an extention and a pay(useful) load part with time slot repeatedly.Yet the added bit that each concentrated time slot kept is unnecessary, because the functional character of each added bit all is repeated in each time slot.For each concentrated time slot, a corresponding extention is arranged, wherein, the information in each extention bit is identical for each concentrated time slot.Therefore, for the multi-slot operation, whole concentrated pay(useful) load is P=Nx ((all bit/serial datas)-(added bit/serial data)).As finding, a large amount of wastes of bit have appearred in the multi-slot method.
Fig. 1 is the block diagram of a communication system, and the system protocol in this system carries out work according to the present invention.
Fig. 2 is the diagram of downstream signal flow structure.
Fig. 3 is the diagram of upward signal flow structure.
Fig. 4 is the diagram according to the signal flow structure of preferred implementation of the present invention.
Fig. 5 is the diagram according to the signal flow structure of second embodiment of the present invention mode.
Fig. 6 is the diagram how different time slot groups of concentrating realizes the several examples of second kind of execution mode of the present invention.
Concentrated TDM/TDMA time slot method of the present invention be with a kind of avoid in concentrating traditional multi-slot method of TDM/TDMA time slot the mode of intrinsic redundancy.By implementing the present invention, originally the bit of wasting by redundancy in the TDM/TDMA time slot of concentrating can be used to increase the bit in the pay(useful) load, so just make each serial data can have more information to transmit, and/or allow in serial data, to carry out error correction, for example forward error correction.
The communication system of representing among Fig. 1 110 can be used the TDM/TDMA system protocol according to a kind of preferred implementation of the present invention.The key component of communication system 110 is central control section 120 and user's interface device 150.User's interface device 150 is connected to user's house usually, as shown in Figure 1.User's interface device 150 is connected to coaxial cable 152, and coaxial cable 152 is connected to Fiber Node 140, and Fiber Node 140 is coupled to central control section 120 by fiber optic cables 142.
In preferred implementation of the present invention, many user's interface devices 150 will be connected to coaxial cable 152.All comprise a cable transceiver in each user's interface device 150, it is designed to according to system protocol work, and this system protocol comprises the revision version of cable access control system provided by the invention (CACS) agreement in a preferred embodiment.In the user's interface device 150 any one all can be designed to or corresponding to the expansion of a basic symmetric protocol or an asymmetric agreement.In either case, a cable user lead-in wire (drop) of user's interface device 150 terminated communications systems 110 and packed so that for good and all be installed on user's the house.User's interface device 150 also has been equipped with one or more interfaces to support different user's building services, the telephone equipment of standard for example, cable TV (CATV) equipment junction box personal computer or the like.
The optical fiber node 140 that coaxial cable 152 is coupled to central control section 120 is changed between the electric territory of the light territory of optical networking and coaxial cable two-wayly.
Central authorities' control section 120 is the devices that often are called as control centre, and its receiving video signals is CATV for example, MPEG-1, MPEG-2, HDTV, health transmission, break (off-the-air) TV broadcasting and other TV programme and video information, among Fig. 1 they are labeled as video signal source 160.Central authorities control section 120 also with different data source (170) and telephone networks (180), for example ISDN and PSTN communicate.This just allows central control section 120 to provide descending cable TV signal to user's interface device 150, the upstream and downstream conversion of data, voice frequency telephone and visual telephone.
By central control section 120 and user's interface device 150, no matter allow the communicating between users that is connected to communication system of any number in communication system 110, be to be directly connected to communication system 110 or EO 122 switches by describing below by coaxial cable 152.
Telephone network 180 communicates by terminal installation (EO) 122 and central control section.The Digital Subscriber Loop carrier system that EO 122 supports standards is the system described in Bellcore file TR-NWT-000303 (124) and the TR-NWT-001203 (126) for example.EO 122 represents a digital telephone exchange that is connected to digital telephone switching network (not shown).
Data source 170 communicates by data switching exchane 128 and central control section 120.Data switching exchane 128 is packet switching processors, and it provides the channel of serving user's interface device 150 and different public or private data network and the interconnection between the server.Data switching exchane 128 comes and CCU (cable control section) 130 by the data link of carrying out suitable Local Area Network agreement, and different transmitter receiver (transceiver) 138,136 and 134 communicates.
CCU 130 provides all necessary function to come back-up system agreement (for example by CACS that the present invention revised).All flow directions of CCU 130 terminations and from the signaling and the control information of user's interface device 150, and manage the operation of all RF (radio frequency) channel, link conversion etc.CCU 130 also with loop plant interfaces from EO 122, realize that on these equipment multiplexed/multichannel of professional and signaling channel is decomposed, and all flow directions of termination/from the control information of EO 122.CCU 130 comes the broadcasting of executive control system information by system protocol, alarm, access, confirm and the logic function of ciphering process that this system protocol is associated a data net address in appropriate users line appearance characteristic among the identity of user terminal and the EO 122 or the data switching exchane 128.
RF combiner 132 combination from the downstream signal of a plurality of transmitters and bridge joint upward signal to a plurality of receivers.RF combiner 132 is by CPX (cableport transceiver), be coupled to CCU 130, wherein each CPX 134 comprises a digital transmitter receiver, it provides the TDM/TDMA/FDD (time division multiplexing of symmetry to central control section (control centre) terminal, time-division multiple access (TDMA), Frequency Division Duplexing (FDD)) carrier wave right.RF combiner 132 also is coupled to CCU 130 by CPR (cableport receiver) 136, and wherein each CPR 136 comprises a digital receiver it offers central control section (control centre) terminal with one in the TDMA/FDD carrier wave set up-link carrier.BCT (broad band cable transmitter) 138 is coupling between CCU 130 and the RF combiner 132, and each BCT 138 comprises a digital transmitter, and it provides the descending 30Mb/s carrier wave of TDMA/FDD carrier wave set to central control section terminal.
Conv/Comb (CATV switch/combiner) 139 will arrive assigned frequency and the composite signal in the cable frequency domain from the conversion of signals of video signal source 160 and RF combiner 132, and using them is to modulate a fiber carrier to optical fiber node 140 by the downlink transfer of fiber optic cables 142., be transformed into correct RF frequency and be delivered to RF combiner 132 by demodulation from the uplink optical fibers carrier wave of optical fiber node 140 by conv/comb 139.
Fig. 2 and Fig. 3 are respectively two descending time frames (201 and 202) and two up time frames (301 and 302) of the defined signal flow of wired communication system 110 employed system protocols among Fig. 1.The system descending agreement comprises the continuous time frame of a large amount of serial transfers.These structures also are the today of employed traditional TDM/TDMA protocol architectures in the cable telephony communication system.As shown in Figure 2, downstream signal circulation is everlasting and is sent in the scope of 50～750Mhz, and upstream signal flow normally sends in 5～30Mhz scope.
The downstream signal stream of Fig. 2 is designed to the transfer system control signal, the telephone signal of digital signal and number format.Upstream signal flow among Fig. 3 can transmit visual signal, system's control, and optical signal, they all are number formats.According to traditional wired communication system form, CACS for example, for each frame of uplink and downlink signal flow, the duration of time frame is redefined for 2.5 milliseconds (ms).Each frame all is divided into a large amount of discrete a plurality of time slots, and wherein the overall width (on the time) of all discrete a plurality of time slots equals the duration of time frame.In CACS, each frame has 8 time slots, and per second has 400 frames.The carrier frequency separation signal flow is 600kHz, and it uses quadriphase PSK (QPSK) modulation of 2 bits/sym, and total chip rate is 384k-sym/sec.Total bit rate is 768kb/s, and pay(useful) load is Nx64kb/s, and wherein for the situation of the maximum 512kb/s of every carrier wave, N is less than or equal to 8.Each descending time slot has 240 bits in each serial data structure.Exist a particular frame and sequence of time slots and particular carrier wave frequency to interrelating.In a single wired communication system, all require frame and slot synchronization for all descending carriers, uplink requirement and downlink transmission synchronous are for timing adjustment will be dynamically carried out in the correct reception of control centre.
Each time slot in the downstream signal stream of a traditional wired communication system TDM/TDMA protocol architecture comprises that all downlink data string 203 is formed among Fig. 2, and it is expressed as the time slot " 0 " of time slot 202 among Fig. 2.Equally, a traditional wired communication system TDM/TDMA agreement comprises the composition of upstream data string 303 among Fig. 3, and it is expressed as the time slot " 0 " of time frame 302 among Fig. 3.To understand the composition of downlink data string 203 and upstream data string 303 better with reference to following Table I.
Table one zone name abbreviation width (bit) effect synchronizing channel SYC 25 frame synchronization (under 25/14 on) control channel CC 9 links control (under 9/2 on) slow channel SC 26 links control subscriber signaling Fast Channel FC 160 pay(useful) loads, user data/signaling error control channel ECC 20 error-detecting guard channel GC, 8 energy slopes and serial data protection differential coding DE 2 modulator phase references
Now with particular reference to Fig. 2, the SYC of downlink data string 203, CC and SC comprise a downlink data crossfire 204, and ECC comprises a downlink data crossfire tail 205.The FC of downlink data string 203 represents pay(useful) load 206.Equally in Fig. 3, GC, the DE, SYC, CC and the SC that are positioned at 303 beginnings of upstream data string have formed the header 304 of upstream data string, at the ECC of ending place of upstream data string 303 and the telegram end 305 that GC has formed the upstream data string.The FC of upstream data string 303 represents pay(useful) load 306.
With reference now to Fig. 4,, is illustrated in 402 in six multi-slot channel sequence sets.As indicated, each in the multi-slot channel of concentrating all comprises header as defined above, a pay(useful) load and a telegram end.In this specific example, when header and telegram end at length do not define, multi-slot channel be upstream or in downstream data flow relation not.Can be easy among Fig. 4 see, although explained when the set of time slot being discussed as the front, header 404,406,408,410,412,414 include same information, they all are repeated, and in time frame in occupation of valuable bit.Equally, telegram end 416,418,420,422,424 and 426 all include identical information and are repeated, have therefore wasted available bit in time slot.
Therefore, preferred implementation of the present invention has been deleted repetition bits unnecessary in header and the telegram end, therefore just allows pay(useful) load can use more bits, to increase an amount of information in the serial data.
In a preferred embodiment of the present invention, provide a header in the time slot of a given number will being concentrated initial, wherein header comprises synchronizing channel, control channel and slow channel in the downlink data string.In the upstream data string, header has comprised guard channel, differential coding, synchronizing channel, control channel and slow channel.The place that begins at first time slot provides header.Header in the time slot in all multi-slots of concentrating of this header and other is identical, therefore needn't repeat header for the time slot in any subsequent set.Similar.Ending place at the time slot of concentrating provides telegram end.Because this telegram end is identical with the telegram end of the time slot that concentrate the front, so need not the repetition telegram end in other any position of the time slot of concentrating.Therefore, all serial datas in the time slot of concentrating are coupled between the telegram end of the header of concentrating the time slot section start and concentrated time slot ending place continuously, then need not each bit of repetition header and telegram end betwixt.In preferred embodiment, only synchronizing channel repeats in each pay(useful) load place.
Should be noted that, by comprise in each pay(useful) load (FC) synchronizing channel (SYC), the present invention can realize present wired communication system for example wired communication system 110 and need not do change on the hardware.Only need to do the change of software or firmware.
By concentrating time slot, discharged added bit and come transmission information according to preferred implementation of the present invention.What table 2 was represented is to use the bandwidth multiplication that preferred implementation of the present invention obtained on traditional multi-slot method of carrying out the time slot set.
Table two
Descending up
Pay(useful) load
1Bit rate
2Pay(useful) load
1Bit rate
2
Newly/old new/old ratio timeslot number is new/old new/old ratio
160/160 64/64 1.000 1 160/160 64.0/64 1.000
386/320 150/128 1.172 2 386/320 154.4/128 1.206
590/480 236/192 1.229 3 612/480 244.8/192 1.275
805/640 322/256 1.258 4 834/640 335.2/256 1.309
1020/800 408/320 1.275 5 1064/800 425.6/320 1.330
1235/960 494/384 1.286 6 1290/960 516.0/384 1.344
1450/1120 580/448 1.295 7 1516/1120 606.4/448 1.354
1665/1280 666/512 1.301 8 1742/1280 696.8/512 1.361
1 bit 2Kb/s
Can see from table 2, concentrate under every kind of situation of a more than time slot that up gain is greater than descending gain, this is because the SYC of upstream signal flow has only 14 bits, and the SYC of downstream signal stream has comprised 25 bits.
What Fig. 5 represented is second kind of implementation method of the present invention.As in Fig. 4, concentrating the multi-slot method representation of six time slots is 502, and wherein each time slot of concentrating comprises a header, a pay(useful) load and a telegram end.In second kind of execution mode of the present invention of Fig. 5, there are not synchronizing channel and each will be by the pay(useful) load associated of concentrating, the pay(useful) load of the time slot that each is concentrated is continuous coupled between header and telegram end, and synchronizing channel is comprised among the concentrated time slot header.Can come the channel allocation of time slot how to concentrate for example according to the second kind of execution mode of the present invention among Fig. 6.
Second kind of implementation method of the present invention requires for example to do some on the wired communication system 110 in the existing wired communication system change (be not on basic structure shown in Figure 1, but on the specific implementation of some parts) of hardware and software and firmware.Because second kind of execution mode only has SYC in header, so can in the time slot of concentrating, transmit more information.In addition, the opening of the bit of the SYC by former repetition can be carried out the error correction of significant front and back and improve the wired communication system transmission performances.Fig. 3 is the comparison between second kind of implementation method and the multi-slot method.
Table three
Descending up
Pay(useful) load
1Bit rate
2Pay(useful) load
1Bit rate
2
Newly/old new/old ratio timeslot number is new/old new/old ratio
160/160 64.0/64 1.000 1 160/1?60 64/64 1.000
400/320 160/128 1.250 2 400/320 160/128 1.250
640/480 256/192 1.333 3 640/480 256/192 1.333
880/640 352/256 1.375 4 880/640 352/256 1.375
1120/800 448/320 1.400 5 1120/800 448/320 1.400
1360/960 544/384 1.417 6 1360/960 544/384 1.417
1600/1120 640/448 1.429 7 1600/1120 640/448 1.429
1840/1280 736/512 1.438 8 1840/1280 736/512 1.438
1 bit 2Kb/s
Except the advantage of above mentioned second kind of execution mode, by using second kind of execution mode, the concentrated time slot of 2X can transmit user profile with the speed of 160kb/s, it is the B channel and the D channel of 1SDN circuit basic rate, surplus with 16kb/s to be to be used for other purposes, for example Kuo Zhan SC and ECC.In addition, in the CACS agreement, the DS0 of a 64kb/s provides by every 2.5ms 20 bits.Therefore:
-in the time slot that a 2X concentrates, can transmit 2.5DS0 ' s.
-in the time slot that a 3X concentrates, can transmit 4.0DS0 ' s.
-in the time slot that a 4X concentrates, can transmit 5.5DS0 ' s.
-in the time slot that a 5X concentrates, can transmit 7.0DS0 ' s.
-in the time slot that a 6X concentrates, can transmit 8.5DS0 ' s.
-in the time slot that a 7X concentrates, can transmit 10.0DS0 ' s.
-in the time slot that a 8X concentrates, can transmit 11.5DS0 ' s.In addition, the user's interface device 150 with two transceivers can transmit 23 in 24 channels of T1 line and the multi-slot method needs 3 transceivers completely.Can transmitting completely according to second kind of execution mode of the present invention, three transceivers in a user's interface device 150, E1 circuit multi-slot method then requires 4 transceivers.
The another one advantage of second kind of execution mode of the present invention is exactly can obtain extra bandwidth allow realizing integrated grouped channels agreement, so the business of the business of circuit mode and packet mode can transmit in the right different time-gap operation of carrier wave.Therefore, the packet mode business is sent out in the time slot of concentrating and is sent out in the other time slot of business at time frame of circuit mode.
Claims (9)
1. method comprises:
The time frame that pre-sets duration in the communication system in time-based agreement is divided into a large amount of discrete a plurality of time slots, wherein total width (in time) of a plurality of discrete time slots of all quantity equals pre-set duration, and has concentrated discrete a plurality of time slots (concentrated time slot) of giving determined number; And
Section start at the time slot of concentrating provides a header, is identical for all time slot headers of concentrating here, all need not the repetition header in other any place of time slot of concentrating.
2. device comprises:
A transceiver allows to install at any amount of communicating between users by this in communication system, and wherein transceiver uses a system protocol; And
System protocol definition time frame, each time frame that has pre-set duration is divided into a large amount of discrete time slots, total width of a plurality of time slots of all quantity duration of equaling to pre-set wherein, concentrated (time slot of concentrating) for discrete a plurality of time slots of determined number, wherein the section start at the time slot of concentrating provides header, and all need not the repetition header in other any place of time slot of concentrating.
3. according to the device of claim 2, wherein ending place at the time slot of concentrating provides telegram end, and other all need not the repetition telegram end Anywhere at the time slot of concentrating.
4. according to the device of claim 3, for each time slot in the time slot of concentrating, synchronizing channel and the pay(useful) load repetitive sequence with synchronizing channel-pay(useful) load between header and telegram end is coupled.
5. according to the device of claim 3, wherein for each time slot of the time slot of concentrating, pay(useful) load is coupling between header and the telegram end, and wherein for each time slot of the time slot of concentrating, all pay(useful) loads are coupling between header and the telegram end continuously.
6. the system protocol that includes the communication system of a large amount of time frames, each time frame that has pre-set duration is divided into a large amount of discrete time slots, total width of a plurality of time slots of all quantity duration of equaling to pre-set wherein, concentrated (time slot of concentrating) for discrete a plurality of time slots of determined number, wherein the section start at the time slot of concentrating provides header, and all need not the repetition header in other any place of time slot of concentrating.
7. according to the system protocol of the communication system of claim 6, wherein ending place at the time slot of concentrating provides a telegram end, and all need not the repetition telegram end in other any place of time slot of concentrating.
8. according to the system protocol of the communication system of claim 7, for each time slot in the time slot of concentrating, synchronizing channel and pay(useful) load between header and telegram end with the repetitive sequence coupling of synchronizing channel-pay(useful) load.
9. according to the system protocol of the communication system of claim 7, for each time slot in the time slot of concentrating, its pay(useful) load is coupling between header and the telegram end, and all pay(useful) loads of each time slot in the time slot of concentrating coupling continuously between header and telegram end.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 97119657 CN1179043A (en) | 1996-09-20 | 1997-09-19 | Variance changeble time slot width in TDM/TDMA system |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US717.466 | 1996-09-20 | ||
| CN 97119657 CN1179043A (en) | 1996-09-20 | 1997-09-19 | Variance changeble time slot width in TDM/TDMA system |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101873198A (en) * | 2010-06-12 | 2010-10-27 | 中兴通讯股份有限公司 | Method and device for constructing network data packet |
| CN106681938A (en) * | 2012-10-22 | 2017-05-17 | 英特尔公司 | Control messaging in multislot link layer flit |
-
1997
- 1997-09-19 CN CN 97119657 patent/CN1179043A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101873198A (en) * | 2010-06-12 | 2010-10-27 | 中兴通讯股份有限公司 | Method and device for constructing network data packet |
| CN106681938A (en) * | 2012-10-22 | 2017-05-17 | 英特尔公司 | Control messaging in multislot link layer flit |
| CN106681938B (en) * | 2012-10-22 | 2020-08-18 | 英特尔公司 | Apparatus and system for controlling messaging in multi-slot link layer flits |
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